Multi shotgun fix (#8460)

* Multi-barrel shotgun fix

* multi-recoil support

* @Nullable for everything

core/src/mindustry/entities/pattern/ShootSummon.java

@@ -14,9 +14,7 @@ public class ShootSummon extends ShootPattern{
     }
 
     @Override
-    public void shoot(int totalShots, BulletHandler handler){
-
-
+    public void shoot(int totalShots, BulletHandler handler, @Nullable Runnable barrelIncrementer){
         for(int i = 0; i < shots; i++){
             Tmp.v1.trns(Mathf.random(360f), Mathf.random(radius));